using System;

namespace ConsoleApp1
{
    internal class Program
    {
        static void Main(string[] args)
        {
            int hall = int.Parse(Console.ReadLine());
            int food = hall * 2;
            double drinksPrice = food * 0.85;
            double other = (food + drinksPrice) / 7;


            double expenses = hall + food + drinksPrice + other;
            Console.WriteLine($"{expenses:F2}");
        }
    }
}